Vegetation along urban strees – is it just trees?

I have written a lot about trees in the urban environment, and I can certainly continue to write about them forever more, though when I stumbled upon the study I am to write about below I thought it would be interesting to touch upon vegetation beyond the realm of trees. Of course, the benefits trees provide, and the issues they create, are well understood, and there will always be a torrent of new research articles dealing with their presence in the urban setting. However, I am not aware of such an abundance of research for shrubs and other types of vegetation that may exist within urban environments. This is probably not all too surprising given trees are simply bigger and more noticable than other types of vegetation, though when we work with trees we also will generally work with shrubs, grasses, and so on. Combined, or even exclusively, such vegetation (and the form adopted – formal or ‘wilded’) will impact upon the lives of residents, and understanding exactly how is always going to be vital to their successful incorporation into an urban landscape. In this instance, the residents of two German cities (Berlin and Cologne) are the focus.

In Cologne, the authors asked passers-by (a total of 108 were questioned) on a main arterial road (see the below image) just outside of the inner portion of the city how they perceived roadside vegetation (with regards to what they valued in terms of the functions the vegetation provides), what types of roadside vegetation they knew about and preferred, amongst other related topics (including how they thought vegetation established within the urban environment). The passers-by were stopped and questioned over the course of three weekdays from the morning through to the evening, during summer. All answers were written down either by them, or by the authors. 56% of passers-by who answered the questions were below 30 years of age, and 58% were male.

This was the site used by the authors for their Cologne study. We can see vegetation occupying different ‘tiers’, with some higher canopy trees with smaller shrubs beneath (some appear to be coniferous, in the foreground).

The Berlin study was somewhat different, and whilst it also was conducted along a similar main arterial road on a summer day (which had wilded vegettion growing along the pathways, below the trees – see the image below), it asked different questions. Principally, the questionnaire provided to the passers-by was standardised, though some open-ended questions did feature. For example, the main bulk of the questionnaire was asking the individuals what type of vegetation cover they thought would work best on the arterial road they were walking down (no vegetation, maintained vegetation, wilded vegetation, or no preference). However, individuals could give reasons as to why they chose the answer they did, and were also asked what they thought about the current ‘wild’ appearance of the roadside vegetation.

This was the exact location of the Berlin survey. All passers-by who stopped to answer the questions thus, in response to the open-ended question asking for their thoughts on the street’s current view, formed their opinion from this vista.

For the Berlin study, 40% of respondents were beloe 30 years of age, and gender distribution was almost equal. 74% of the individuals lived either near to the street or in an inner city borough of Berlin, and 78% were familiar with the street to some degree.


In Cologne, just over half (52%) of the respondents considered trees to be the main vegetation type that feature along roads. The remaining 48% therefore detailed shrubs, perennials, and grasses – some individuals were specific to the species, as well. Furthermore, a wide array of landscaping features were also identified by the respondents, with flower beds, tree pits, and planting tubs being but three examples. In terms of how the individuals thought the vegetation had become established, the vast majority (87%) considered artificial planting to be the cause (be it through public or private hands). Only 13% suggested that natural regeneration could have led to the street vistas of Cologne.

A great number of the surveyed individuals also valued roadside vegetation as important, and for a variety of reasons (see the below table). Responses ranged from their presence being good for amenity to being beneficial for improving air quality, though most answers related to the vegetaton’s amenity value. So positive were the answers that many had a desire to see a greater amount of roadside vegetation of all types, of which some answers pushed a greater number of ‘wilded’ scenes more akin to a rural and naturalised scene. The reason for this ‘wilded’ desire varied, though answers included for the benefit of insects such as bees, to simpy being more interesting to the eye and making the streets more “lively”.

This table compares how respondents valued different ecosystem services, across the two cities.

For respondents in Berlin, 48% considered the current ‘wild’ appearance of the street undesirable, and suggested it should be more formal in character (dubbed ‘urban devotees’). Conversely, 43% liked the vegetation as it was (dubbed ‘wilderness enthusiasts’). The remaining 8% did not mind, or were undecided. Therefore, there is certainly a similar mix of individuals who like ‘wilded’ streets and those who don’t. Unspurprisingly, it was the wilderness enthusiasts that most routinely saw the vegetation on the street as greatly improving the landscape’s character, because they considered the street to have a greater association with nature (a total of 40% of all respondents responded in such a manner). On the other hand, the ~30% of individuals who didn’t like the ‘wilded’ vegetation were more frequently from the urban devotee group (and this group cited the poor safety and amenity of the ‘wilded’ area as their reasons for such an opinion). The below table shows the disparity of opinion.

A breakdown of how urban devotees and wilderness enthusiasts valued the current ‘wilded’ streetside vegetation.

Across both sities, neither age or gender were significant in determining how an individual viewed vegetation cover.

Concluding remarks

From the results detailed, there is no question that there is a wide range of opinion regarding what vegetation types are most valued by individuals, and the form that these vegetation types adopt (formal or ‘wilded’). It is entirely evident that there will always be a significant minority of people who do not appreciate the vegetation cover an urban area possesses, and it is also evident that people will value vegetation presence for different reasons (though mostly, it is for the aesthetic benefit provided – even then, what is considered as aesthetic beauty differs from person to person). Despite this, more vegetation (in general) on streets was in demand.

It is nonetheless curious that a good portion of those surveyed valued ‘wild’ vegetation (particularly in Berlin, and likely because individuals were more routinely exposed to such vegetation cover), though perhaps still considered this ‘wilded’ character as originating from man’s intervention. Only a small selection of respondents understood that the vegetation on streets may also regenerate naturally. By a similar token, the fact that many respondents recognised that trees are not the only type of urabn vegetation cover that may grace street scenes is suggestive of a need to incorporate complex landscaping vistas into urban sites – simply having canopy cover is not ‘enough’, perhaps. At the same time however, the desire of many for safe and formal landscapes may mean that constituent vegetation is maintained to some degree. Perhaps there is scope to have both more formal and ‘wilded’ vegetation types, assuming a street can accomodate such diversity (this requires size and desire).

Source: Weber, F., Kowarik, I., & Säumel, I. (2014) A walk on the wild side: Perceptions of roadside vegetation beyond trees. Urban Forestry & Urban Greening. 13 (2). p205-212.

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Vegetation along urban strees – is it just trees?

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